Conveyor roll device for preliminarily bending sheet glass

ABSTRACT

A glass sheet that has been heated nearly to a softening point thereof is preliminarily bent by a conveyor roll device while being fed along a feed path to a bending press. The conveyor roll device has a succession of first straight rolls spaced along the feed path for supporting a central region of the glass sheet, and a succession of second straight rolls spaced along the feed path for supporting a marginal edge portion of the glass sheet. The second straight rolls are vertically tilted through progressively differing angles, respectively, along the feed path with respect to the first straight rolls. The first and second straight rolls alternate with each other along the feed path.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a conveyor roll device that ispositioned between a heating furnace and a bending press, forpreliminarily bending a sheet of glass that has been heated by and fedfrom the heating furnace and which will be fed into and pressed to abent shape by the bending press.

2. Description of the Prior Art

Bent glass sheets such as automobile window glass panels are produced byfeeding a glass sheet heated by a heating furnace to a bending presshaving upper and lower press dies, between which the heated glass sheetis pressed to a desired bent shape. If, however, a flat glass sheet werepressed directly to a final bent shape, the bent glass sheet would tendto crack or would not be bent accurately to desired shape.

One solution to the above problem is disclosed in U.S. Pat. No.4,749,399. According to the disclosed solution, the peripheral edge of aheated glass sheet fed from a heating furnace is supported on aseparable ring mold, and after the peripheral edge of the glass sheet ispreliminarily shaped by the ring mold, the glass sheet is pressed to adesired bent shape between upper and lower dies. If the glass sheet isto be bent to a relatively large curvature, only the peripheral edge ofthe heated glass sheet is supported by the ring mold for a relativelylong period of time until the glass sheet is pressed by the upper andlower dies. Therefore, the heated glass sheet is liable to beundesirably deformed due to gravity before it is pressed to shape.

Japanese patent publication No. 55-49018 shows a succession of conveyorrolls for feeding a glass sheet from a heating furnace into a bendingpress. Each of the conveyor rolls comprises a curved core and a flexiblesleeve rotatably fitted over the curved core. When the heated glasssheet is fed by the conveyor rolls, the glass sheet is preliminarilybent to a curved shape by the conveyor rolls. The conveyor rolls thusserve as bending rolls for preliminarily bending the glass sheet. Theflexible sleeves are loosely fitted over the corresponding cores inorder for the flexible sleeves to be able to rotate on the respectivecores for feeding the glass sheet. Consequently, when the conveyor rollsfeed the glass sheet, the flexible sleeves vibrate on rotation aroundthe cores, straining the glass sheet to the point where some undesirableoptical distortions may develop in the finally bent glass sheet. Anotherproblem is that a different set of curved conveyor rolls must be usedwhen glass sheets of a different curvature are to be produced.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a conveyorroll device which can preliminarily bend a sheet of glass to an accurateshape without deformations and optical distortions.

According to the present invention, there is provided an apparatus forpreliminarily bending a glass sheet heated nearly to a softening pointthereof while feeding the glass sheet along a feed path to a bendingpress, the apparatus comprising a plurality of first straight rollsspaced along the feed path for supporting a central region of the glasssheet, and a plurality of second straight rolls spaced along the feedpath for supporting a marginal edge portion of the glass sheet, andadjusting means for vertically tilting the second straight rolls withrespect to the first straight rolls.

According to the present invention, there is also provided a conveyorroll device for feeding a glass sheet heated nearly to a softening pointthereof along a feed path to a bending press, comprising roll means forsupporting the glass sheet on a succession of first straight rollsurfaces engaging a central region of the glass sheet and a successionof second straight roll surfaces engaging a marginal edge portion of theglass sheet, and adjusting means for tilting the second straight rollsurfaces with respect to the first straight roll surfaces.

According to the present invention, there is also provided a glassbending apparatus comprising a press for bending a glass sheet, and aconveyor roll device for feeding the glass sheet which has been heatedto a temperature near its softening point by a furnace along a directionto the press and for preliminarily bending the glass sheet prior topressing of the glass sheet by the press, the conveyor roll devicecomprising a sequence of rolls which are rectilinear where they contactthe glass sheet and arranged with their axes at differing angles ofinclination to a horizontal plane so as to give the glass sheet arequired prebend until the glass sheet is fed to the press.

The above and further objects, details and advantages of the presentinvention will become apparent from the following detailed descriptionof preferred embodiments thereof, when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a glass sheet bending systemincluding a conveyor roll device according to an embodiment of thepresent invention which is disposed between a heating furnace and abending press;

FIG. 2 is a schematic plan view of the conveyor roll device according tothe first embodiment;

FIG. 3 is a side elevational view taken along line III--III of FIG. 2;

FIG. 4 is a side elevational view of a first conveyor roll of theconveyor roll device according to the first embodiment;

FIG. 5 is a side elevational view of a second conveyor roll of theconveyor roll device according to the first embodiment;

FIG. 5A is a perspective view of a glass sheet that is preliminarilybent by the conveyor roll device shown in FIG. 5;

FIG. 6 is a plan view of a power transmitting system for the conveyorroll device according to the first embodiment;

FIG. 7 is a side elevational view showing the manner in which a glasssheet is preliminarily bent by the conveyor roll device according to thefirst embodiment;

FIG. 8 is a side elevational view showing the manner in which the glasssheet is transferred to transfer rolls;

FIG. 9 is a side elevational view of a conveyor roll device according toa second embodiment of the present invention;

FIG. 9A is a perspective view of a glass sheet that is preliminarilybent by the conveyor roll device shown in FIG. 9;

FIGS. 10A through 10C are schematic plan views showing the manner inwhich the conveyor roll device shown in FIG. 9 operates to preliminarybend a glass sheet;

FIG. 11 is a fragmentary perspective view of a conveyor roll deviceaccording to a third embodiment of the present invention;

FIG. 12 is a side elevational view of a conveyor roll device accordingto a fourth embodiment of the present invention; and

FIG. 12A is a perspective view of a glass sheet that is preliminarilybent by the conveyor roll device shown in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a glass sheet bending system includes a conveyorroll device 10 according to an embodiment of the present invention forpreliminarily bending a glass sheet.

The glass sheet bending system also has a heating furnace 1 for heatinga glass sheet nearly to its softening point and a bending press 2 forpressing the heated glass sheet to a desired bend shape.

The bending press 2 is positioned downstream of the heating furnace 1with respect to the direction in which the heated glass sheet is fedfrom the heating furnace 1 along a feed path A. The bending press 2comprises a vertically movable upper die 3, a vertically movable lowerdie 4 disposed below the upper die 3, a vertically movable concave ringmold 5 extending around the lower die 4 for supporting the peripheraledge of a glass sheet G, and a plurality of transfer rolls 6 verticallymovably located in the ring mold 5 for supporting the glass sheet G thathas been preliminarily bent by the conveyor roll device 10.

The transfer rolls 6 are composed of inner rolls 6a and outer rolls 6b(see FIG. 2) that are arranged to provide an upper support surfacecomplementary in shape to the preliminarily bent glass sheet G. Theheated glass sheet G discharged from the heating furnace 1 is fed by theconveyor roll device 10 onto the transfer rolls 6. Then, the peripheraledge of the glass sheet G is supported by the ring mold 5, after whichthe glass sheet G is pressed to shape between the upper and lower dies3, 4.

The conveyor roll device 10 will be described in detail below withreference to FIGS. 2 through 6.

The conveyor roll device 10 has a pair of left and right conveyor rollassemblies disposed one on each side of the central axis B of the feedpath A. Since the left and right conveyor roll assemblies aresymmetrical in configuration, only one of the left and right conveyorroll assemblies will be described below with reference to FIGS. 2through 5.

As shown in FIG. 2, the conveyor roll assembly comprises a plurality offirst spaced straight conveyor rolls 11 extending perpendicularly to thefeed path A and a plurality of second spaced straight conveyor rolls 12also extending perpendicularly to the feed path A. The first and secondconveyor rolls 11, 12 alternate with each other along the feed path A.As shown in FIGS. 2 and 3, the second conveyor rolls 12 are tilted abouttheir inner ends that are closer to the center of the feed path A,successively through differing angles with respect to a horizontalplane. More specifically, the second conveyor rolls 12 are tiltedthrough progressively greater angles in the direction away from theheating furnace 1.

As shown in FIG. 4, each of the first conveyor rolls 11 is rotatablymounted on an arm 15 that is supported on a frame 13 for angularadjustment about a shaft 14 on the outer end of the first conveyor roll11 with respect to the frame 13. Rotation of a main shaft 17 that isrotated by a motor 16 (see FIG. 6) is transmitted to each of the firstconveyor rolls 11 through successive bevel gears 18 and a universaljoint 19.

As shown in FIG. 5, each of the second conveyor rolls 12 is rotatablymounted on an arm 21 that is supported on the frame 13 for angularadjustment about a shaft 20 on the inner end of the second conveyor roll12 with respect to the frame 13. A vertical arcuate guide plate 22having an arcuate guide groove 23 defined therein is attached to anouter edge of the arm 21. The frame 13 supports a bracket 24 with asetscrew 25 supported thereon which extends through the arcuate guidegroove 23. When the setscrew 25 is loosened, the arm 21 and hence thesecond conveyor roll 12 can be angularly adjusted with respect to theframe 13. When the setscrew 25 is tightened, the arm 21 and the secondconveyor roll 12 are fixed at a desired angle with respect to the frame13. Rotation of the main shaft 17 rotated by the motor 16 is transmittedto the second conveyor roll 12 through bevel gears 26 and a flexibleshaft 27. Actually, as shown in FIG. 6, the rotation of the main shaft17 of the right conveyor roll assembly is transmitted through the bevelgears 26 and the flexible shafts 27 to the second conveyor rolls 12 ofthe left conveyor roll assembly, and the rotation of the main shaft 17of the left conveyor roll assembly is transmitted through the bevelgears 26 and the flexible shafts 27 to the second conveyor rolls 12 ofthe right conveyor roll assembly. In this manner, the flexible shafts 27are not required to be sharply bent in transmitting the rotation to thesecond conveyor rolls 12.

The glass sheet G that has been heated by the heating furnace 1 ispreliminarily bent by the conveyor roll device 10 as follows:

The first conveyor rolls 11 are held substantially horizontally, and thesecond conveyor rolls 12 are tilted successively through progressivelygreater angles in the direction away from the heating furnace 1. Thus,the second conveyor roll 12 closest to the heating furnace 1 is tiltedthrough the smallest angle, and the second conveyor roll 12 closest tothe bending press 2 is tilted through the greatest angle.

The heated glass sheet G discharged from the heating furnace 1 is thenfed by the conveyor roll device 10. As the heated glass sheet G travelson the first and second conveyor rolls 11, 12, it is progressivelypreliminarily shaped thereby as shown in FIG. 7. More specifically,opposite marginal edge portions of the glass sheet G are bent upwardlythrough progressively greater angles by the second conveyor rolls 12 ofthe left and right conveyor roll assemblies. The glass sheet G that hasbeen preliminarily bent by the conveyor roll device 10 is then deliveredonto the transfer rolls 6.

As shown in FIG. 8, the outer rolls 6b of the transfer rolls 6 aretilted upwardly with respect to the inner rolls 6a thereof so that theyjointly provide an upper support surface for snugly supporting the glasssheet G in a manner to keep the preliminarily bent configurationthereof.

After the glass sheet G has been placed on the transfer rolls 6, thetransfer rolls 6 are lowered to an imaginary-line position C (FIG. 8),transferring the glass sheet G onto the ring mold 6. At this time, thetransfer rolls 6 are retracted in recesses 4a (see FIG. 1) defined inthe lower die 4. Thereafter, the upper die 3 is lowered, and the lowerdie 4 and the ring mold 5 are lifted for pressing the glass sheet G to adesired final bent shape.

The conveyor roll device 10 is suitable for preliminarily bendingrectangular glass sheets into a shape whose opposite marginal edges arebent with a uniform radius of curvature (i.e., R₁ =R₂ in FIG. 5A).

The first conveyor rolls 11 may not be angularly adjustable, but may befixed in a completely horizontal direction. In this case, the firstconveyor rolls 11 of the left and right conveyor roll assemblies may bejoined together.

Since the second conveyor rolls 12 are independently tiltable throughdesired angles, the conveyor roll device 10 can be adjusted topreliminarily bend a glass sheet G highly accurately to a desired curvedshape. As the first and second conveyor rolls 11, 12 support theunderside of the glass sheet G without vibrations, the glass sheet G issubstantially free from deformations and optical distortions after it ispreliminarily bent. The conveyor roll device 10 is also capable ofadjusting the speed at which a glass sheet G is preliminarily bent, byaltering the angles of the second conveyor rolls 12.

FIG. 9 shows a conveyor roll device according to another embodiment ofthe present invention.

The conveyor roll device shown in FIG. 9 differs from the conveyor rolldevice shown in FIG. 5 in that each of the second conveyor rolls 12 isrectilinearly movable perpendicularly toward and away from the centralaxis B of the feed path A. As shown in FIG. 9, the arm 21 is angularlymovably mounted on a bracket 30 that is connected to the bracket 24 by ahorizontal plate 31. The bracket 24 is not connected to the frame 13.The brackets 30, 24 have respective lead screw nuts threaded over ahorizontal lead screw 32 rotatably mounted on the frame 13. Thehorizontal lead screw 32 extends perpendicularly to the central axis Bof the feed path A. The horizontal lead screw 32 has an outer endconnected to the main shaft 17 through bevel gears 26. When a glasssheet G is fed by the conveyor roll device, the second conveyor rolls 12are synchronously moved perpendicularly to the feed path A by the leadscrew 32. Specifically, before the glass sheet G is fed by the conveyorroll device, the second conveyor rolls 12 are positioned in an innerposition as shown in FIG. 10A. When the glass sheet G is fed by theconveyor roll device, the second conveyor rolls 12 of the left and rightconveyor roll assemblies move away from each other as shown in FIG. 10B.After the glass sheet G enters the bending press, the second conveyorrolls 12 return to the inner position as shown in FIG. 10C.

The conveyor roll device shown in FIG. 9 is suitable for preliminarilybending trapezoidal glass sheets into a shape whose opposite marginaledges are bent with a uniform radius of curvature (i.e., R₁ =R₂ in FIG.9A).

The lead screws 32 may be connected to a different motor so that theymay be rotated independently of the motor 16 which rotates the secondconveyor rolls 12. Therefore, the lead screws 32 may be used to adjustthe position of the second conveyor rolls 12 with respect to, or thedistance thereof from, the central axis B of the feed path A, ratherthan moving them in synchronism with the feeding of the glass sheet G.The conveyor roll device with the lead screws 32 used to adjust theposition of the second conveyor rolls 12 is suitable for preliminarilybending rectangular glass sheets of different sizes into a shape whoseopposite marginal edges are bent with a uniform radius of curvature.

FIG. 11 shows a conveyor roll device according to still anotherembodiment of the present invention. In FIG. 11, the arm 21 is angularlymovably mounted on the bracket 30, and the lead screw 32 is threadedthrough the lead screw nut in the bracket 30 and a lead screw nut 33 onthe plate 31. The bracket 24 is mounted on a base 34 movably disposed onthe horizontal plate 31. The horizontal plate 31 has a pair of parallelarcuate guide grooves 35 defined therein, and the base 34 ispositionally adjustably fastened to the horizontal plate 31 by setscrews36 that extend through the guide grooves 35. The arcuate guide grooves35 extend about the vertical axis of the bracket 30 around which the arm21 can be turned. Therefore, when the setscrews 36 are loosened, the arm21 and hence the conveyor roll 12 can be angularly moved about thevertical axis of the bracket 30, i.e., the angle between the centralaxis B of the feed path A and the vertical plane in which the conveyorroll 12 is tiltable can be varied. When the setscrews 36 are tightened,the vertical plane in which the conveyor roll 12 is tiltable isangularly fixed with respect to the central axis B of the feed path A.

FIG. 12 shows a conveyor roll device according to yet another embodimentof the present invention. The conveyor roll device shown in FIG. 12differs from the conveyor roll device shown in FIG. 9 in that the arm 21is angularly movable about its inner end in synchronism with the feedingof the glass sheet G. More specifically, the arm 21 is operativelycoupled to the motor 16 through bevel gears 37, a worm gear mechanism38, and the lead screw 32. One of the bevel gears 37 is fixed to theinner end of the arm 21, and the other bevel gear 37 meshing therewithis coupled to the worm gear mechanism 38 that is mounted on the bracket30. The worm gear mechanism 38 is operatively connected to the leadscrew 32. Therefore, when the glass sheet G is fed by the conveyor rolldevice, the second conveyor rolls 12 are moved away from the centralaxis B of the feed path A by the lead screws 32, and at the same timeare tilted, i.e., vertically angularly moved with respect to the firstconveyor rolls 12.

The conveyor roll device shown in FIG. 12 is suitable for preliminarilybending trapezoidal glass sheets into a shape whose opposite marginaledges are bent with different radii of curvature (i.e., R₁ ≠R₂ in FIG.12A).

In FIG. 1, the bending press 2 is positioned outside of the heatingfurnace 1. However, the principles of the present invention are alsoapplicable to a glass sheet bending system in which a bending press ispositioned within a heating furnace.

Although there have been described what are at present considered to bethe preferred embodiments of the invention, it will be understood thatthe invention may be embodied in other specific forms without departingfrom the essential characteristics thereof. The present embodiments aretherefore to be considered in all respects as illustrative, and notrestrictive. The scope of the invention is indicated by the appendedclaims rather than by the foregoing description.

What is claimed is:
 1. An apparatus for preliminarily bending a glasssheet heated nearly to a softening point thereof by a heating furnacewhile the glass sheet is fed relative to a central axis in a feed pathdirection from the heating furnace to a bending press, said glass sheethaving a central portion and a marginal edge portion, the apparatuscomprising:a plurality of spaced-apart first straight rolls forsupporting the central region of the glass sheet; and a plurality ofspaced-apart second straight rolls for supporting the marginal edgeportion of the glass sheet, said second straight rolls having first endscloser to the central axis and second ends farther from the centralaxis; means for moving the second straight rolls including the first andsecond ends toward and away from the central axis; and means forvertically tilting the second straight rolls through progressivelydiffering angles, respectively, along the feed path direction withrespect to the first straight rolls.
 2. An apparatus according to claim1, wherein said first and second straight rolls are alternately locatedwith respect to each other.
 3. An apparatus according to claim 1 whereinsaid tilting means includes means for adjusting said second straightrolls about the first ends thereof.
 4. An apparatus according to claim1, wherein said tilting means comprises means for progressivelyadjusting angles of said second straight rolls along the feed pathdirection.
 5. An apparatus according to claim 1, wherein said tiltingmeans comprises means for adjusting angles of said second straight rollsindependently of each other with respect to said first straight rolls.6. An apparatus according to claim 1, further comprising drive means forrotating said first and second straight rolls about their own axes tofeed the glass sheet along the feed path direction.
 7. An apparatusaccording to claim 6, wherein said tilting means comprises means forautomatically adjusting angles of said second straight rolls withrespect to said first straight rolls in synchronism with the rotation bysaid drive means of said first and second straight rolls.
 8. Anapparatus according to claim 1, wherein said tilting means comprisesmeans for automatically adjusting angles of said second straight rollswith respect to said first straight rolls in synchronism with themovement by said moving means of said second straight rolls.
 9. Anapparatus according to claim 1, wherein said first straight rolls havefirst ends closer to the central axis and second ends farther from thecentral axis, said tilting means including means for inclining saidfirst straight rolls about the second ends thereof.
 10. An apparatusaccording to claim 1, further comprising means for angularly cantingsaid second conveyor rolls horizontally with respect to the centralaxis.
 11. A conveyor roll device for moving a glass sheet heated nearlyto a softening point thereof relative to a central axis in a feed pathdirection, said glass sheet having a central portion and a marginal edgeportion, said device comprising:left and right roll assemblies disposedon first and second sides of the central axis, respectively, said leftand right roll assemblies for supporting the glass sheet on a successionof first straight roll surfaces engaging the central region of the glasssheet and a succession of second straight roll surfaces engaging themarginal edge portion of the glass sheet on the first and second sidesof the central axis, respectively; said left roll assembly includingfirst means for tilting said second straight roll surfaces throughprogressively differing angles, respectively, along the feed path, onthe first side of the central axis in a first direction with respect tosaid first straight roll surfaces, said right roll assembly includingsecond means for tilting said second straight roll surfaces throughprogressively differing angles, respectively, along the feed path, onthe second side of the central axis in a second direction with respectto said first straight roll surfaces.
 12. A conveyor roll deviceaccording to claim 11, wherein on each of the first and second sides,said first straight roll surfaces alternate with said second straightroll surfaces along the feed path direction.
 13. A conveyor roll deviceaccording to claim 11, wherein each of said first and second tiltingmeans comprises means for progressively adjusting angles of said secondstraight roll surfaces along the feed path direction.
 14. A conveyorroll device according to claim 11, wherein each of said first and secondtilting means comprises means for adjusting angles of said secondstraight roll surfaces independently of each other with respect to saidsecond straight roll surfaces.
 15. A conveyor roll device according toclaim 11, further comprising first and second drive means for rotatingsaid first and second straight roll surfaces to feed the glass sheetalong the feed path direction on the first and second sides of thecentral axis, respectively.
 16. A conveyor roll device according toclaim 15, wherein said first and second tilting means each comprisesmeans for automatically adjusting angles of said second straight rollsurfaces with respect to said first straight roll surfaces insynchronism with the rotation by said first and second drive means ofsaid first and second straight roll surfaces, respectively.
 17. Aconveyor roll device according to claim 11, wherein said left and rightroll assemblies further comprise first and second means for moving saidsecond straight roll surfaces on the first and second sides of thecentral axis toward and away from the central axis, respectively.
 18. Aconveyor roll device according to claim 17, wherein said first andsecond tilting means each comprises means for automatically adjustingangles of said second straight roll surfaces with respect to said firststraight roll surfaces in synchronism on the first and second sides ofthe central axis with the movement by said first and second moving meansof said second straight roll surfaces, respectively.
 19. A conveyor rolldevice according to claim 11, further comprising:first and second drivemeans for rotating said first and second straight roll surfaces to feedthe glass sheet along the feed path direction on the first and secondsides of the central axis, respectively; and first and second means formoving said second straight roll surfaces on the first and second sidesof the central axis toward and away from the central axis, respectively;said first and second tilting means comprising means for automaticallyadjusting angles of said second straight roll surfaces with respect tosaid first straight roll surfaces in synchronism on the first and secondsides of the central axis with the rotation by said first and seconddrive means of said first and second straight roll surfaces on the firstand second sides of the central axis and the movement by said first andsecond moving means of said second straight roll surfaces on the firstand second sides of the central axis.